Krell Amplifier Repairs

Krell KSA100 MkII Stereo Power Amplifier

Resistors and transistors on one channel were found blown. Two 75Ω and six 1Ω resistors required and MJ15003\4, three MJ15030's and two MJ15031's transistors were used.

Krell KSA200 Stereo Power Amplifier

This was tripping the mains supply or just dropping the soft start relay out. Found an MJE power transistor with its front blown off and 3 o\p transistors s\c on the front 't' bar, while removing the MJE 15030 noticed the screws holding this and adjacent MJE 15031 were loose and the (nylon) screws holding the MJE pairs on the heat sink snapped, due to heat probably. When these were replaced it powered up okay, but then noticed that 3 of the 6 't' bars were extremely hot - excessively so even for a class A Krell. The quiescent was high at a max of 400mA on the hot ones. In the immediate interests of keeping it together reduced it to around 230 mA. It needed 4ba nylon bolts for the MJE's or 6-32 unc as they were originally.